Apparatus and method for testing circuit modules

ABSTRACT

Circuit modules comprise a carrier surface with components mounted thereon. A testing apparatus for these modules comprises a magazine for hosting a row of circuit modules. The row is pushed into a gripper of a pickup mechanism by means of a press-on member. As a consequence, the orientation of the magazine can be horizontal. The gripper removes the gripped modules in a direction in line with the row. The press-on member preferably comprises a rotatable press-on plate which rotates along with the row of modules if it starts to fan out, but at the same time pushes the row back so that significant fanning is prevented.

FIELD OF THE INVENTION

This invention relates to an apparatus and method for manipulating andtesting circuit modules each comprising a carrier surface withcomponents arranged thereon. The invention relates in particular to thetesting of memory modules for PCs (Personal Computers). Examples of suchmemory modules are known under the name of SIMMs, DIMMs, etc.

BACKGROUND OF THE INVENTION

Memory modules are tested before they are mounted in PCs or sold. Suchtesting is preferably done in an automated manner and in serialproduction, with a number of modules being introduced simultaneouslyinto a testing apparatus, to be subsequently contacted one by one withelectrical testing terminals for performing a functional test. Dependingon the result of the test, the modules are subsequently sorted intoproperly working and improperly working modules. U.S. Pat. No. 5,704,489discloses an apparatus for testing memory modules. This apparatuscomprises a magazine into which a plurality of modules stacked onto eachother can be introduced. This magazine stands substantially verticallyon the apparatus, so that the stack of memory modules rests on theunderside of the magazine. At the underside of the magazine is amechanism for dropping the modules one by one from the magazine onto atable. On the table is a slide which proceeds to push the modules intothe test terminals.

The apparatus of U.S. Pat. No. 5,704,489 is of modular design, so thatit is suitable to be converted if after handling a first batch of memorymodules of a first type, a second batch of memory modules of a secondtype having different dimensions or a different connection are to betested.

The apparatus mentioned has a number of disadvantages. Firstly, thenumber of memory modules that can be simultaneous placed in the magazineis rather limited, in particular if modern types of memory modules areinvolved. This is because these modern types of modules comprise, on thecarrier surface thereof, adjacent the edge of the carrier surface, acomponent (an EPROM) which projects higher above the carrier surfacethan the other components. As a consequence, the memory modules fan outwhen being stacked: the stack becomes highest on the side of theprojecting component and much lower on the opposite side. If significantfanning is involved, that is, fanning through a large angle and/orcumulative fanning of more than a few a circuit modules, this limits themaximum number of memory modules that can be properly stacked. Further,the weight of high stacks presses onto the lower modules, which aresupported only on the sides and therefore may easily be damaged. Thisalso limits the number of modules that can be stacked.

Secondly, the known machine has the disadvantage that the modules, byfalling onto the table, can get damaged. Thirdly, the resetting inbetween batches of different types, despite the modular design, is stillconsiderable, because the height of the table must be adjusted to theheight of the components on the carrier surface. Fourthly, the mechanismof the known machine does not allow modules that differ mutually in theheight of the components on them, to be jointly placed in the magazinefor testing. Fifthly, the mechanism of the known machine only lendsitself for testing one module at a time.

SUMMARY OF THE INVENTION

It is one object of the invention to provide an apparatus and method fortesting circuit modules in which a larger number of circuit modules canbe placed in the magazine. It is another object of the invention toprovide an apparatus and method for test circuit module in which thechance of damage to the circuit modules is reduced.

It is a further object of the invention to provide an apparatus andmethod for testing circuit modules in which the resetting times areshortened.

The invention provides an apparatus for testing circuit modules eachcomprising a carrier surface with components mounted thereon, whichapparatus is provided with:

-   -   a magazine for hosting a row of circuit modules with the carrier        surfaces onto each other;    -   a pickup mechanism for separating an individual circuit module        from the row for connecting the individual circuit module to        test terminals for performing a functional test on the        individual circuit module;    -   a press-on member for pressing on the row in a direction towards        the pickup mechanism, the press-on member exerting a press-on        force on the carrier surface of a circuit module at an end of        the row in the magazine.

By pressing on the row of modules with the press-on member, significantfanning is prevented. As a result, a larger number of modules can beplaced in the magazine. Preferably, the magazine is placed substantiallyhorizontally, so that the force which the modules exert onto each otheroriginates substantially from the press-on member and not from theweight of the stacked modules. This reduces the chance of damage.

In an apparatus according to an embodiment of the invention, the pickupmechanism comprises a gripper into which the circuit modules are pushedby the press-on member. Thus, the gripper itself does not need toperform the pickup movement, which renders the gripping of the circuitmodule more reliable, with less risk of damage.

In an embodiment, the gripper, with a gripped module, moves away fromthe row at least for a part in the direction of the prolongation of therow (that is, along the direction of the press-on force). The grippertoo is preferably carried to the row in this direction for the purposeof gripping. Alternatively, the gripper could move the gripped moduletransversely to the row, that is, in a direction parallel to the carriersurface, but this leads to a greater chance of damage in that componentson the different modules thus move along each other. Likewise, if thegripper were to approach the row in this transverse direction, thechance of incorrect gripping is greater.

In an embodiment of the apparatus according to the invention, thegripper comprises a yoke which further serves as a stop to hold the rowof modules when the gripper is in front of the row. The yoke onlyengages the edge of the carrier surface of the front module in the row.Thus, different types of modules, with components or other elevations ofdifferent heights can be handled without the apparatus needing to bereset for the purpose. Further, the gripper is preferably provided withmovable jaws to clamp the module in the gripper and with cams whichengage in standardized recesses in memory modules for PCs. As a result,the risk of a module falling from the gripper is virtually precluded.

Preferably, the apparatus according to the invention comprises aclamping device to clamp one or more modules which are immediateneighbors of the gripped module when the gripper moves away from therow. Alternatively, knives could be used which are moved partly betweenthe gripped module and its immediate neighbor, but the clamping devicerequires less space between the modules and prevents tilting of themodules, which may happen when using knives between the modules.

In an apparatus according to an embodiment of the invention, thepress-on member comprises a press-on plate which is rotatable, so thatit rotates along if the modules were to fan out. What is prevented bythe rotation is that the press-on plate presses onto a fixed point. Inan embodiment, the magazine comprises a guide profile about which themodules hinge if they fan out. The rotation axis of the press-on plateis preferably so positioned that the plate, if it rotates along, presseson that side of this “hinge” where the row, upon fanning out, becomesthickest.

The press-on plate is preferably adapted to be swung clear and backagain, so that if behind the press plate additional modules are loadedinto the magazine (into a loading space where they are not pressed uponyet), the press-on plate can be swung clear from behind the row and canbe swung back in again behind the loaded addition modules. Thus, minimalinterruption is required for loading additional modules. Preferably, themagazine comprises side guides, which engage in notches on the side ofthe modules to prevent the modules from being pressed out of the row. Tofacilitate loading, these side guides preferably do not continue intothe loading space.

These and other objects and advantages of the apparatus and methodaccording to the invention will be further described with reference tothe following figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an overview of the apparatus according to the invention;

FIG. 2 shows an overview of the magazine;

FIG. 3 shows a side elevation of the gripper;

FIG. 4 shows a front view of the magazine;

FIG. 5 shows a top plan view of the magazine;

FIG. 6 shows a detail of the magazine in top plan view.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an overview of the apparatus. The apparatus comprises amagazine 10, a test connector 12, a transport mechanism 14, a dischargebin 16 and a discharge mechanism 18. Shown in the magazine 10 are a rowof memory modules 100. Further, the apparatus comprises a press-on plate102 in the magazine 10, a piston 104 for energizing the press-on plate102 and a swinging connection 106 between the piston 104 and thepress-on plate 102. Arranged along the walls of the magazine 10 areprofiles 108. The transport mechanism 14 comprises a gripper 140, asupport 142, a vertical actuator 144 and a horizontal actuator 146.Shown in the gripper 140 is a circuit module 15. Further, the apparatuscomprises a control computer (not shown) for the coordination andinspection of the operation of the different parts.

In use, a row of circuit modules 100 is placed in the magazine 10, forinstance by an operator. The press-on plate 102 pushes the row ofmodules 100 to an end of the magazine 10. The transport mechanism 14brings the gripper 140 to the end of the magazine 10, where the grippergrips a circuit module from the row 100. The transport mechanism 14 thenmoves the circuit module 15 in the gripper 140 to the test connector 12and pushes the circuit module 15 into the test connector 12.

Via the test connector 12, a series of signals are sent to the module 15and response signals from the module 15 are read out to test theelectronic functionality of the circuit module 15. This is done, forinstance, by means of a test process that is known per se. The specifictest process is not relevant to the invention.

Upon completion of the test process, the transport mechanism 14 movesthe gripper 140, with the circuit module 15 therein, to dischargemechanism 16, in which the gripper 140 deposits the module. Thedischarge mechanism 18 comprises, for instance, two conveyor belts, afirst one for circuit modules 15 which have been found in order in thetest process and a second one (not shown) for circuit modules 15 whichhave not been found in order. The discharge mechanism 16 transports themodule 15 to discharge bin 16 for modules found in order or to a furtherdischarge bin (not shown) for modules not found in order. As analternative to discharge bins, also intermittent belts can be mounted(not shown). On these, the modules 15 are stacked overlapping likeroof-tiles.

FIG. 2 shows the magazine portion of the apparatus in more detail. Shownare guides 20 a, b, a row of circuit modules 22, press-on plate 24,clamps 26 a, b, a draw spring 27, profiles 28 a, b provided on guides 20a, b, and a bottom plate 29 a of the magazine with a profile 29 barranged thereon.

In use, the press-on plate 24 serves to push the row of circuit modules22 in the direction of the viewer of FIG. 2 (to the “front” of FIG. 2).Although FIG. 2, for the sake of visibility, shows the press-on plate 24at some distance from the row of modules 22, this press-on plate 24 willoperatively abut against the row of circuit modules 22 (at the “back” inFIG. 2). From piston 104, via connection 106, a force of, for instance,10 Newton is exerted on the press-on plate 24. The press-on plate 24thus pushes the circuit modules 22 forwards. At the front, the circuitmodules 22 are stopped by the gripper (not shown in FIG. 2). This willbe discussed further hereinafter. During pushing, the guides 20 a, bguide the circuit modules on the sides, and the bottom plate 29 a guidesthe circuit modules from below.

The carrier surfaces (generally PCBs) of memory modules for PCs includerecesses at standardized positions. At positions where these recessesare located in the circuit modules in the row 22, profiles 28 a, b, 29 bare arranged which continue from the front to the back (the profiles 28a, b do not continue all the way to the back of the magazine). Theprofiles 28 a, b, 29 b aid in guiding the circuit modules. The profiles28 a, b on the side guides (and the side guides themselves) chieflyserve to prevent, if necessary, movement of the circuit modules 22 invertical direction. Preferably, there is only one profile 29 a on thebottom plate; more profiles can give rise to the danger of jerking.Press-on plate 24 prevents fanning of the circuit modules 22. The factis that many memory modules for PCs comprise a relatively high component(an EPROM) on the carrier surface and in the vicinity of the edgethereof. The relatively high component is higher than the othercomponents on the carrier surface. Due to this high component, thecircuit modules in the row of circuit modules 22 tend to skew, so thatthe row 22 on one side, for instance on the side of a first guide 20 b,continues further backwards than on the side of the second guide 20 a.In the magazine, the circuit modules hinge about the profile 29 b in thebottom plate. The press-on plate 24 presses on the circuit modules 22 atleast at a point between the profile 29 b in the bottom plate 29 a andthe high component. The exact location of this point depends on wherethe plate touches the components on the carrier surface. As aconsequence, the row of circuit modules 22 is pressed upon without themodules essentially fanning.

The press-on plate 24 is preferably rotatably mounted about an axis 25which is located substantially above the profile 29 b, centrally betweenthe guides 20 a, b. Due to its rotatability, the press-on plate 24 canrotate along if the circuit modules fan initially or later to a minorextent. The press-on force is thus concentrated in the vicinity of thecenter. It has been found that in the case of a non-rotatable press-onplate 24, under some circumstances, with some types of circuit modules,there is a risk of the circuit modules being pushed out of the row 22.Presumably, this is because the point of action where the press-on plate24 exerts force on the circuit module is displaced, due to the rotation,in the direction of the side of the row of circuit modules 22 where itis thickest due to fanning. (This point of action depends on thecomponents on the circuit modules, but is in the vicinity of a pointfrom which the normal to the carrier surface points to the center of theaxis 25.) As long as the center of the axis 25 does not lie further fromthe profile 29 b on the bottom plate 25 than the distance between thiscenter and the contact face of the press-on plate 25 that is in contactwith the row of circuit modules, different types of circuit modules withall kinds of unevenness can be handled. However, if it is known that thecircuit modules all have their highest point on one side of the carriersurface, the center of the axis can also be placed between the profileand that side of the carrier surface. A use of a press-on plate 24 of athickness of from 1 to 2 cm is preferred to obtain a favorable pressurepoint on the row 22. Preferably, at least the edges of the contact faceof the press-on plate 24 that is in contact with the row of circuitmodules (at least the edges proximal to the guides 20 a, b) are roundedoff, or provided with obtuse angles, such that they do not hook on theedge of components on the carrier surface of a circuit module, but slideover it.

Preferably , it is possible to load new circuit modules into themagazine while the apparatus is operating normally and hence press-onplate 24 is pressing on a row of circuit modules 22. To that end, thecombination of piston 104 and connection 106 is adapted to be swungclear. If for instance an operator has loaded circuit modules behind thepress-on plate 24, the pressure is removed from the piston 104, and theoperator swings the press-on plate 24 clear from the space between theguides 20 a, b. The operator proceeds to slide the press-on plate 24 toa point behind the newly loaded circuit modules and swings the press-onplate 24 back between the guides 20 a, b again. Thereupon the pressureagainst the piston 104 is built up again. This is preferably donegradually, over a period of 10 seconds to 1 minute, which reduces therisk of misalignment of circuit modules.

Preferably, the profiles 28 a, b on the guides 20 a, b do not continueall the way to the rear side of the magazine, but leave clear a loadingspace without profiles on the side guides in the magazine. As a result,it is possible to load the magazine at the back from above by placingcircuit modules between the guides. Further, the bottom plate 29 a inthe loading space preferably has more than one profile 29 b. In thisway, modules 22 can only be loaded into the magazine to stand levelalong their length if they are properly oriented, that is, not rotatedthrough 180° about the vertical axis. Further, the circuit modulescannot at that point come to stand askew in the magazine. Only one ofthese profiles 29 b on the bottom plate 29 a continues into that part ofthe magazine where the press-on plate 24 is operative. This preventsjamming of the circuit modules there.

Preferably, the position of the side guides 20 a, b and clamps 26 a,b isadjustable to different types of circuit modules, each type having adifferent width. Press-on plate 24 does not need to be adjustable andcan merely have a width of less than the width of circuit modules of thenarrowest type. It has been found that in that case too the pushingmechanism works satisfactorily.

FIG. 3 shows a front view of the gripper. The gripper comprises a yoke30, on which movable gripper jaws 32 a, b are mounted. Further, fittedto the gripper is a block 38 on an adjusting screw. The grippercomprises an energization (not shown) to reciprocate the gripper jaws 32a, b along the yoke (to the left and right in FIG. 3). Provided on theyoke 30 are pins 31 a, b and provided in the gripper jaw are slots 34 a,b to guide the movement. Provided on the gripper jaws 32 a, b are lips36 a, b. Arranged between the lips 36 a, b and the yoke 30 are profiles(cams) 37 a, b. Preferably, the profiles 37 a, b are arranged on themovable gripper jaws 32 a, b, but alternatively the profiles 37 a, b canbe arranged on the yoke 30.

FIG. 4 shows a front view of the magazine. The front view shows theguides 20 a, b, the profiles 28 a, b, the bottom plate 29 a, and theprofile 29 b, the spring 27, clamps 26 a, b, with rubbers 40 a, bthereon and a circuit module 42.

FIG. 5 shows a top plan view of the magazine. The top plan view showsguides 20 a, b, press-on plate 24, axis 25, connection 106, profiles 28a, b, bottom plate 29 a, profile 29 b and clamps 26 a, b.

FIG. 6 shows an enlarged quasi cross section (parts not to scale) of acorner of the magazine in combination with the gripper in top plan view.Of the magazine are shown: one of the guides 20 b, one of the clamps 26a, b, the bottom plate 29 a. Of the gripper 140, there are shown crosssections of the yoke 30 and of the movable gripper jaw 32 a. Furthershown is the circuit module 42, with a component 61 thereon. Finally, anext circuit module 60 is shown.

In operation, transport mechanism 14 brings the gripper 140 opposite themechanism as shown in FIG. 6, that is, such that the surface of the yoke30 proximal to the circuit modules 42, 60 is above the bottom plate 29a. The yoke 30 projects into the space formed beyond and in line withthe guides 20 a, b, so that the yoke constitutes a stop against whichthe circuit module 42 is pressed by the press-on plate 24 via the row ofcircuit modules 22. As a result, the circuit module 42 cannot be pressedbeyond the yoke 30. The yoke 30 only projects by a limited distance intothe space formed beyond and in line with the guides 20 a, b,specifically not so far that it touches any component 61 on the circuitmodule 42.

Initially, the gripper jaws 32 a, b are slid outwards, and the clamps 26a, b are pushed outwards (by an actuator not shown). Thus, the circuitmodule 42 can be pushed beyond the lips 36 a, b, with its carriersurface against yoke 30. The block 38 prevents the circuit module 42from bending in the middle. If desired, the block 38 can be adjusted tothe height of the components on the circuit module 42, but in practicethis has been found to be hardly necessary.

Next, the clamps 26 a, b are no longer pushed outwards. These clamps 26a, b are now pulled towards each other by the draw spring 27, so thatthey clamp next circuit modules 60 succeeding the circuit module 42which is being pressed against the yoke (only one next circuit module isshown).

Also the gripper jaws 32 a, b are moved towards each other, so that thelips 36 a, b move over the carrier surface of circuit module 42. Theprofiles 37 a, b in the gripper engage in the recesses of the circuitmodule 42 which were guided earlier by side profiles 28 a, b (sideprofiles 28 a, b do not project outside guides 20 a, b). As a result,the circuit module 42 is fixed in the gripper. The transport mechanism14 thereupon moves the gripper 142 with the circuit module 42 away fromthe magazine, in a direction in line with the row, that is, such thatthe distance between the carrier surfaces of the gripped circuit module42 and the next circuit module 60 from the row increases upon initiationof the movement of the circuit module 42 out of the row. Thus, there isno contact between these modules 42, 60 during movement, and hence nochance of damage (naturally, the direction of movement does not need tobe entirely in line with the row, as long as the direction of movementhas a component in line with the row.) Next, the transport mechanism 14moves the gripper to the test connector 12, and pushes the circuitmodule 42 into the connector 12 for the test. The clamps 26 a, b remainpulled towards each other, as long as the gripper is not in front of themagazine, and thereby prevent the next circuit module 60 from fallingout of the magazine. In principle, every time when a module has beentested, the gripper 140 can be moved back to the magazine, while thetested modules adjacent to the magazine are placed on the dischargemechanism which is controlled depending on the result of the test. Thus,the discharge of modules does not require any additional movements ofthe transport mechanism. Without departing from the invention, however,a plurality of test connectors 12 can be used, with the gripper pickingup consecutive circuit modules and placing them in test connectors whilecircuit modules are being tested in one or more other test connectors.

It will be clear that the apparatus shown enables serial testing ofcircuit modules and specifically memory modules for PCs, without thecircuit modules needing to fall out of the magazine to be processed. Nouse is made of gravity. All forces that are needed for processing can beaccurately controlled and are hardly, if at all, dependent on the numberof circuit modules standing in the magazine.

1. An apparatus for testing circuit modules each comprising a carriersurface with components mounted thereon, which apparatus is providedwith: a magazine for accommodating a row of circuit modules with thecarrier surfaces onto each other; a pickup mechanism for separating anindividual circuit module from the row for connecting the individualcircuit module to test terminals for performing a functional test on theindividual circuit module; a press-on member for pressing on the row ina direction towards the pickup mechanism, the press-on member exerting apress-on force on the carrier surface of a circuit module at an end ofthe row in the magazine.
 2. An apparatus according to claim 1, whereinthe magazine is disposed such that a normal to the carrier surfaces ofthe modules in the row is oriented substantially perpendicularly to theforce of gravity.
 3. An apparatus according to claim 1, wherein thepickup mechanism is provided with a gripper and is arranged to positionthe gripper, during pickup, relative to the magazine, such that afurther circuit module at a further end of the row is pushed into thegripper by the press-on force.
 4. An apparatus according to claim 3,wherein the pickup mechanism is arranged to move the further modulegripped in the gripper, away from the row in a direction having at leasta component in line with the row.
 5. An apparatus according to claim 3,wherein the gripper comprises a yoke against which the press-on forcepushes up the further circuit, the yoke including a recess, such thatonly of the further circuit module only opposed edge portions of thecarrier surface on which no components are arranged are pushed upagainst the yoke.
 6. An apparatus according to claim 5, wherein on theyoke movable gripper jaws are mounted which are arranged, after thefurther circuit module has been pushed against the yoke, to move towardseach other to embrace at least the edge portions of the carrier surface.7. An apparatus according to claim 3, for testing circuit modules whichinclude a notch in each of the edge portions, wherein the gripperincludes cams to engage in the notches.
 8. An apparatus according toclaim 3, provided with an energizable clamping device for clampingopposed edges of the carrier surface of one or more of the circuitmodules at the further end of the row next to the further circuitmodule, the apparatus being arranged to energize the claming device atleast when the gripper is not in front of the magazine and to releasethe clamping device during a period of the time when the gripper is infront of the magazine.
 9. An apparatus according to claim 1, wherein thepress-on member comprises a plate for transmitting a press-on force ontothe carrier surface of the circuit module at the end of the row, theplate being rotatable about a rotation axis parallel to the carriersurface of the circuit modules at the end of the row.
 10. An apparatusaccording to claim 9, for testing circuit modules having a notch in anedge of the carrier surface, wherein the magazine comprises a guideprofile for guiding the circuit modules in the row by their notch overthe guide profile, while the rotation axis makes an angle ofsubstantially ninety degrees with said edge of the carrier surface ofthe modules in the row.
 11. An apparatus according to claim 10, whereina distance between the rotation axis and the guide profile is less thana distance between the rotation axis and a surface of the press-on platewhich comes into contact with the circuit module at the end of the row.12. An apparatus according to claim 1, wherein the press-on member isadapted to be swung clear out of the magazine and to be swung back againinto a portion of the magazine upstream of the row and is adapted to beslideable relative to the row.
 13. An apparatus according to claim 12,wherein the press-on member comprises an energization which, when thepress-on member is being swung clear, is de-energized and, after thepress-on member has been swung back in again, gradually builds up thepress-on force over a time interval of at least 1 second.
 14. Anapparatus according to claim 1, wherein the magazine comprises apress-on space with side profiles for guiding side notches in thecircuit modules of the row and at most one bottom profile for guiding anotch in a lower side of the circuit modules and wherein the magazinecomprises a loading space which via a transition zone continues into thepress-on space, wherein a bottom of the magazine in the loading spacecomprises more than one guide profile for respective notches at thelower side of the circuit modules, and wherein the loading space doesnot comprise any side profiles.
 15. An apparatus according to claim 1,arranged for picking up and testing circuit modules which are memorymodules for PC's.
 16. A method for testing circuit modules, wherein useis made of the apparatus according to claim 1.